In a typical inductively coupled plasma processing reactor, radio frequency (RF) power is delivered to a processing gas within a processing volume. One or more coil antennas disposed on the top of a dielectric window are energized, and the RF energy is transferred to the gas to form a plasma A processing substrate such, for example, as a semiconductor wafer is mounted on the surface of a chuck to which a biasing RF voltage is applied.
When the foregoing approach is adapted to a chemical vapor deposition (CVD) chamber, a problem of undesirable variations—in the film formation upon the substrate surface—can develop if the spatial distribution of RF power to the plasma by the antenna is, itself, non-uniform. Still another problem is that the electrical components formed on the substrate suffer charging damage due to a non-uniform plasma density.
Therefore, the inventors have provided an improved method and apparatus for controlling the spatial distribution of the RF power being delivered to a plasma reactor.